To support the forum with your donation, please check

Main Menu

Solve The Mystery Of The Moving Bullseye

Started by writerman, January 13, 2022, 01:20:18 PM

Previous topic - Next topic


I built a 6.5 Creedmoor with a 24" Ballistics Advantage Heavy Barrel, Aero Precision Upper/Lower, and a quality bolt. Everything's tight regarding the scope mount/screws, nothing touching the free float barrel, ammunition powder weighed precisely because I always do that, quality Barnes 140 Grain bullets, it's an AR10. I have AR's that I can put a dime out at 200 yards consistently, so in this case, I don't believe it's the shooter. Checked everything I could think of. One piece Vortex mount with a PST 5x25x50 Gen II scope. The scope is new. The problem is on every shot the center of aims shifts. I mean, aim to the center, pull Hiperfire ultra smooth trigger, watch the scope, see that the crosshairs are not moving and bam. Shifts point of aim. Up one shot. Down another. To the right another shot. To the left another shot. Cannot adjust the scope to point of aim. I was at first thinking it might be the barrel extension, or crown, because the barrel extension was cut so sharp the edges have torn up my bolt head. But now I think it might be something inside the scope shifting? What has your experience been with this point of aim shifting. Thanks for your help.


If I understand your explanation, it has to be the scope, assuming the mount is fine.

I had a scope drive me nuts one time, it wasn't new, but it was new to me. I sent the scope to the manufacturer who tested it and said it was toast, they sent me a new one. I figure that's why the guy sold the darn thing.


You say powder was weighed precisely.. so your shooting reloads?. What kind of load development have you done to determine that precisely weighed powder charge? If you just picked a random charge out of the manual then you may just be in a scatter node for lack of a better term..


Put the scope on one of your rifles that is already shooting well. Test it to rule it in or out of the equation.


Ah, I could test it out by putting it on a rifle I know shoots well. Good one.
I contacted Vortex and am sending it back for them to confirm. They said I could have accidentally torqued the mount screws too tight. I don't think I did, but I guess that's possible of course. I take my time setting them, and try not to tweak them too much. I also think it might be the barrel. My bolt is toast from the barrel extension cuts, and that may have something to do with it.


Put a new Swaro Z3 on a Ruger 77 left hand 7-08 many years ago.  Was ready to wrap that stick around a tree or drive it as a tomato stake. Calmer heads prevailed.  Swaro made it good.  That combo one of one of my old-school kinda light, woods walking favorites.  Warm walnut soothes my soul.  :)
If you have the shot, take it.


What was wrong with the  Svaro? Did it make any loose parts noise when you shook it after you took it off the rifle? Vortex said they were certain that the scope would be okay, if I heard no loose parts. I didn't hear any, but I still have to test it again.


I am going to take your advice, jvw2008 before sending the scope back to Vortex. I put a New Zeiss scope on the rifle and will test to see if the rifle itself holds aim. If not, I know it's the rifle itself. If so, I know it's the scope. Then I'll send it back. Thanks. Now why didn't I think of that? Oh, I know. Because I can ask the forum. :)


I can almost guarantee you that if you went over 25 inch pounds on those scope rings, you'll not likely be able to hold zero with that scope,